Treatment of wool

ABSTRACT

Wool is rendered shrink-resistant by: A. A PRELIMINARY MILD OXIDATIVE SHRINK-RESIST TREATMENT, PREFERABLY USING A CHLORINE-CONTAINING AGENT, AND B. TREATMENT WITH A CATIONIC POLYELECTROLYTE, PREFERABLY A POLYVINYL IMIDAZOLINE, AND WITH A POLYMER, E.G., A POLYETHYLENE, EMULSION, SO AS TO EXHAUST POLYMER ON TO THE WOOL FIBRES. The treated wool can be dried below 100*C and does not need to be cured.

Umted States Patent [11] 3,811,835 Gallup et a1. May 21, 1974 [5 TREATMENT OF WOOL 2,447,539 8/1948 Rust 8/128 Inventors: Raymond Charles p, 2,467,233 4/1949 Rust 8/128 2,516,055 7/1950 HaIgh et al. 8/128 Attlebom; Rlchard Edward Riley, 2,421,363 5/1947 Young 117/55 New Bedfor both o Mass. 2,468,086 4/1949 Lathan et a1 117/55 [731 Assigneei Pfecjision f g g FOREIGN PATENTS OR APPLICATIONS I Der an 1,074,731 7/1967 Great Britain 8/128 22 F1 d: F b. 8 1971 N OTHER PUBLICATIONS Blow, I. SOC. Chem. Ind. 57, 116-124 T, (1938). [30] Forelgn Priority Data Primary Examiner -George F. Lesmes Feb. 23, 1970 Great Brltam 8039/70 Assistant Examiner j' Cannon U S Cl 8/128 A 8/127 6 /1 R Attorney, Agent, or Firm-Wenderoth, Lind & Ponack 117/55, 117/76 T, 117/DlG. 3, 117/161vA:

117/161 UB, 117/161. UC, 117/161 UP, [57] ABSTRACT 117/161 117/161 [17/161 Wool is rendered shrink-resistant by:

1 17/141 260/823 260/857 260/857 a a reliminar mild Oxidative shrink-resist 1 260/857 UN 260/878 R 260/895 260/897 B p y Int Cl D06m 3/10 D06; 15/36 6 15/60 treatment, preferably usmg a chlorIne-contalnmg agent, and [58] Field of Search 8 33 37 51 3 g" b. treatment with a cationic polyelectrolyte, 13; 3 S preferably a polyvinyl imidazoline, and with a N 161 l6] Pkg/127 6 2128A R polymer, e.g., a polyethylene, emulsIon, so as to 1 exhaust polymer on to the wool fibres. [56] References Cited The treated wool can be dried below 100C and does UNITED STATES PATENTS not need to be Cured 2,328,900 9/1943 Grimm et al 8/l27.6 3 Claims, N0 Drawings 1 TREATMENT or WOOL In the past many shrink-resistant treatments have been proposed which give satisfactory results when the treated articles are washed under mild conditions. However in order to achieve freedom from shrinkage when severe washing conditions are employed, very high dosages of oxidative shrink-resist treatments may be necessary which can give rise to fibre degradation and to interference with dyeing properties. In the case of articles which have been dyed before shrink-resist treatment, substantial loss of dyestuff fastness may occur after the treatment has been applied. A further difficulty may arise in that treated garments which may have satisfactory resistance to shrinkage can suflerv gested including polyethylenes, but it has always been found necessary in the past to employ polyethylenes which contain reactive groups capable of internal cross-linking. Furthermore the only satisfactory way of applying the polyethylenes has been by some form of impregnation process either from an organic solvent, or from aqueous emulsion. Part of the process of treating wool with such polyethylenes has included a stepto cross-link the polyethylene which has been deposited. A commonly employed method has been to subject the treated article to baking at elevated temperatures'usually well in excess of 100C. Such treatment carries the risk of yellowing the wool fibre and has not found ready commercial acceptance.

Preparations containing non-reactive polyethylenes have been used as textile finishing aids and have been prepared as agents which could assist in preventing the pilling of articles containing wool, but to be effective for this purpose large quantities of the polymer have been necessary, which have adversely affected the handle of the treated goods.

We have now founda method of treating wool using successive oxidation and polymer deposition steps which, contrary to expectation, confers a high degree of shrink resistance, and at the same time improves considerably the resistance of the treated article to 'pilling, without however requiring large proportions of polymer or a final high-temperature curing step.

The. present invention providesa process for treating wool in order to render it-shrink-resistant, which process comprises:

a. subjecting the wool to an oxidative shrink-resist pretreatment so as to reduce the shrinkage by from 5 percent to 80 percent, then b. treating the modified wool with a cationic polyelectrolyte and with an aqueous emulsion of an emulsifiable polymer so as to exhaust polymer on to the fibres of the wool, and

.c. drying the thus-treated wool.

This invention is capable of being performed on a batch or a continuous basis, although it is more suited to batch operation. Wool may be treated according to this :process atany stage in its manufacture, e.g., loose W001, top, yarn, knitted or woven fabric, and the treatment may be carried 'out before or after dyeing.

The first step of the process is a substantially uniform treatment of the wool with an oxidising agent, preferably a chlorine-containing oxidizing agent, under acid conditions. Such treatments are well known, and will not be described in detail here. However, it is sufficient for the purpose of this invention to carry out the treatment to a mild degree so as to reduce the felting shrinkage, as measured in the Cubex International Apparatus according to British Standard No. 1955 by from 5 percent to percent compared with the untreated wool. The dosage required to achieve this shrinkage reduction will vary from one sample of wool to another.

The preferred reagent for this treatment is an acidified aqueous solution of an alkali metal dichloroisocyanurate. Other chlorine-containing agents such as an acidified solution of an alkali metal salt of hypochlorous acid or an acidified solution of gaseous chlorine dissolved in water, may be employed. It is possible to use dichloroisocyanurate or hypochlorite in conjunction with potassium permanganate.

The chlorine-containing oxidizing agent may also contain permonosulphuric acid or an alkali metal salt thereof. In this case the treatment process may be carried out under conditions such as those described in British Pat. Specification No. 1,036,107 (Laporte). Such treatments give a whiter product than that obtainable from chlorine-containing oxidizing agents alone.

An alternative oxidative pre-treatment can be carried out using permonosulphuric acid or an acidified alkali metal salt thereof. Such treatments are described in British Pat. Specification No. 716,806.

The oxidizing treatments described above are desirably carried out in the presence of a wetting agent, preferably a non-ionic wetting agent such as a watersoluble polyethylenoxy-alkyl phenol.

After treatment with an oxidizing agent the woollen material may be further treated in an aqueous bath containing an alkali metal salt of sulphurous acid such as sodium sulphite or sodium bisulphite, or mixtures of the two, in order to remove residual chlorine or to neutralize acidity.

At the conclusion of the treatments described above, the treated woollen material should be thoroughly rinsed and is then ready for the next stage.

The second step of the process is the treatment of the modified wool with a cationic polyelectrolyte and with an aqueous emulsion of an emulsifiable polymer which is exhausted on to the fibres of the wool. It is possible to treat the modified wool, first with the cationic polyelectrolyte, and subsequently with the polymer emulsion; but it is preferred according to the invention to treat the modified wool with a mixture of the two reagents, for by this means, in batch operation, complete exhaustion of the polymer is readily achieved.

The polyelectrolyte is a water-dispersable or watersoluble polymer having a plurality of cationic ionizable sites. A number of polyelectrolytes based on polyacrylamide are available commercially, for example, that sold under the Trade Mark Polyteric CA. Watersoluble polyamides may also be used. A preferred class of polyelectrolytes isv that comprising polymers (e.g., having a molecular weight of from 20,000 to 10,000,000 viscosity average) having an exclusively carbon atom backbone to which are attached units ofthe formula:

where A is a C to C alkylene group in which different carbon atoms are linked to the two nitrogen atoms. Such polymers may be prepared by reacting a dior poly-amine with a polymer of a nitrile-containing monomer. A particularly preferred cationic polyelectrolyte is that sold under the Trade Mark Primafloc C7. which is believed to be a polyvinyl imidazoline in the class just described.

A wide variety of polymers may be used in this process, the essential requirement being that they should be emulsifiable in water. Mention may be made of polyacrylates, polyvinyl acetates and copolymers, polyolefins and particularly polyethylenes. Emulsions sold under the Trade Names Bradsyn P.E. (Hickson & Welch), Iberlene P.E. (Harrison Chemicals), Mykon SF (Warwick Chemicals), Vinamul 6000 and 6515 (Vinyl Products) and Calatac VB (I.C.I.) have been employed. In the case of polyethylene emulsions, the polymer should preferably have a melting point of ll05C, a molecular weight below about 5000, an acid number of under 20 and a carbonyl content of not more than 1% C=0 by weight.

Although the polymer may contain reactive sites along its chain, we have found that this is not necessary and indeed may be disadvantageous, as our process does not include a curing step involving cross-linking, and any reactive sites remaining in the polymers when deposited on the fibre could possibly confer undesirable properties to the treated material.

An emulsifying agent will generally be necessary, and we prefer to use a nitrogen-free non-ionic emulsifying agent, the polyethylenoxy-alkylphenols being suitable.

The aqueous polymer emulsion may be cationic, nonionic or anionic. The surface of wool fibres is anionic, and it is known that cationic polymer emulsions will exhaust on to wool fibres. However, such exhaustion does not give rise to significant shrink resistance in the absence of a cationic polyelectrolyte. In the presence of a cationic polyelectrolyte, the exhaustion of cationic polymer emulsions tends to be rather slow and may confer only a moderate degree of shrink resistance on the product.

We prefer to use a non-ionic polymer emulsion. Such emulsions do not exhaust on to woo] (whether or not it has previously been treated with an oxidizing agent) in the absence of a cationic polyelectrolyte, and it is surprising that they do so when a cationic polyelectrolyte is present. In fact the exhaustion process takes place very readily and may be completed under favourable conditions in from 2 to minutes.

' The pH of the exhaustion bath is preferably from 4 to 7, particularly from 5 to 6. Temperature is important, and we prefer to operate at from C to 60C, e.g., C to C; in particular, operation at lower temperatures may not give satisfactory results because of slow rate of exhaustion. The emulsion should be rather dilute, and will generally contain considerably less than I percent w/w solids. Under favourable conditions, exhaustion is rapid and complete; completion of the process can be readily observed because the liquor, which is initially turbid, becomes completely clear.

The amount of polymer that is exhausted on to the wool may be from 0.1 percent to 4.0 percent, preferably 0.75 percent to 2 percent by weight on the weight of the wool. Below 0.1 percent, little additional shrink resistance (over that provided by the oxidation treatment) may be obtained; above 4.0 percent, the handle of the wool may be altered to an undesirable degree. The proportion of polyelectrolyte may be from 0.05 percent to 1.0 percent, preferably 0.1 percent to 0.5 percent by weight on the weight of the wool. Below 0.05 percent, exhaustion of non-ionic polymer emulsions may not readily take place; above 1.0 percent, the handle and dyeability of the wool may be affected. Large amounts of polyelectrolytes have little influence on shrink resistance, and it is therefore preferred to use the minimum amount necessary to achieve satisfactory exhaustion.

Exhaustion is a necessary part of the process of this invention. Deposition of the polymer on to the wool fibres by precipitation or by evaporation of the solvent (or the continuous phase of an emulsion) does not confer significant added shrink resistance on the wool. The term exhaustion has been used to describe the transfer of disperse phase particles from an emulsion or suspension (without breaking the emulsion or suspension) to the fibres of the wool immersed in it; it is not intended to imply that the process must necessarily be complete (i.e., that the supply of disperse phase particles must necessarily be exhausted) although complete exhaustion will generally be convenient in batch operation as providing automatic control over the amount of polymer deposited.

After exhaustion has taken place, excess liquor is removed from the treated wool, e.g., by hydroextraction, and the wool is then dried, preferably at a temperature of not more than 100C, e.g., 80C. Ofcourse, the wool can be dried at higher temperatures if this is desired;

but we have found that higher temperatures do not confer added shrink resistance, and high temperatures are liable, as is well known, to affect the properties of the wool adversely. In particular, no advantage is gained by drying the wool at a temperature above the melting point of the polymer.

The precise mode of action of the polymers in conferring shrink resistance is unknown. No high temperature curing step is required, and indeed the preferred emulsions are made from non-reactive polyethylenes which cannot be cross-linked. The presence of the polyelectrolyte is essential, and presumably it achieves the correct form of deposition and anchorage between the polymer and the wool fibre necessary to confer shrink resistance.

When the process of this invention is performed as a batch operation, the woollen goods are simply immersed in successive baths containing the various treatment liquors. The liquor ratio in the bath is in no way critical to the invention. Liquor to wool ratios of from 5:1 to :1, e.g. 30:1, may be found convenient for both the oxidation and the polymer treatments.

Alternatively, the process may be carried out continuously on a continuous length of woollen goods. The treatment with the chlorine-containing oxidizing agent may be carried out by known means, e. g., by the procedures described in British Patent Specification No. 1,073,441 or 1,098,582. A continuous treatment with permonosulphuric acid may also be used, e.g., by the procedure described in British Pat. Specification No. 1,084,716. The continuous treatment with polymer emulsion may best be carried out using a pad mangle, although application may be made from baths of a conventional backwasher. In either case it is essential that during or after the impregnation step, a significant degree of exhaustion of the polymer on to the fibre should occur before .the treated goods are subjected to further stages of processing, e.g., rinsing, treating with other agents, or drying. The time for this exhaustion to occur will depend both on the nature of the polymer and the properties of the wool being treated, but should not normally exceed minutes.

The invention also includes an aqueous liquor, suitable for use in the process herein described,'which liquor comprises an emulsion of a polymer of acrylic acid or a substituted acrylic acid, a homopolymer or copolymer of vinyl acetate or a polyolefin, and a solution of dispersion of a cationic polyelectrolyte, in an aqueous medium.

The invention also includes wool which has been rendered shrink-resistant by the process herein described.

The following Examples illustrate the invention. The abbreviation o.w.w. stands for on the weight of the wool". LR. stands for liquor ratio". Parts and percentages are by weight unless otherwise stated.

1n Examples 1 to 4, 6 and 7, non-ionic polyethylene emulsions are used; Examples 5 and 8 show the use of cationic and anionic emulsions. In Examples 1 to 4, 7 and 8, the polyelectrolyte was mixed with the polymer emulsion; Example 6 shows treatment of the wool first with polyelectrolyte and then with emulsion. Example 8 shows the use of PVA and acrylate emulsions.

EXAMPLE 1 3 samples of worsted serge were treated with 0.5 per cent (o.w.w.) active chlorine from sodium dichloroisocyanurate at a pH of3.5,.a 30:1 LR. and C. Treatment was carried out until all the chlorine had reacted with the wool. Antichlor treatment was then carried out by addition of 1. percent (o.w.w.) sodium bisulphite. The samples werethen rinsed, removed from the bath, and one was dried at 80C, in a static drier.

The second sample was then treated in a bath containing:

I 1 percent solids (o.w.w.) non-ionic polyethylene emulsion (Bradsyn P.E.), 0.1 percent solids (o.w.w.) polyelectrolyte (Primafloc C7), at a :1 LR. and a pH of 5.0 for 15 minutes at 40C. The pH was adjusted to 5.0 by addition of 10 percent (w/v) orthophosphoric acid.

During the treatment, the liquor was seen to go wa ter-clear, indicating that exhaustion of the polymer had occurred. The sample was then removed, hydroextr'acted, and dried at 80C in a static drier.

A third sample was treated exactly as the second, with the exception that the polyelectrolyte was omitted. The bath remained turbid and did not exhaust, The samples were tested for felting shrinkage in the Cubex lnternational Apparatus according to B.S. 1955, for 60 minutes in 25 litres.

Sample Area Shrinkage Pre-treatment plus polymer and electrolyte 9 Pre-treatment plus polymer 24 Pre-treated only 22 Untreated 35 EXAMPLE 2 2 Samples of fabric,'knitted 2 end-as-l, from a 2/20s worsted spun yarn, were treated with 2.0 percent (o.w.w.) active chlorine from sodium hypochlorite solution at a pH of 3.9, a 30:1 LR. and 25C until all the chlorine had reacted. The samples were then neutralised by addition of 4.0 percent (o.w.w.) sodium sulphite for 20 minutes at 25C, rinsed and hydroextracted.

One was removed and dried at 80C in a static drier. The other was treated with:

0.75 percent solids (o.w.w.) non-ionic polyethylene emulsion (Iberlene P.E.),

0.1 percent solids (o.w.w.) polyelectrolyte (Primafloc C7), at a pH of7 and 15:1 L.R., for 10 minutes at 40C. During this time, the treatment liquor was seen to go water-clear, indicating that the polymer had exhausted on to the wool. The sample was then hydroextracted and dried at 80C in a static drier.

A further sample of the fabric was treated in a polymer solution identical to that used for the second sample, the oxidative pre-treatment having been omitted. The bath exhausted completely and the sample was hydroextracted and dried as before.

Area shrinkages after a minutes, 15 litre Cubex test, were as follows:

Sample Area Shrinkage 0.6 percent (o.w.w.) sodium dichloroisocyanurate,

1.8 percent (o.w.w.) potassium permonosulphate at a 30:1 L.R. at a pH of 5.4, for 10 minutes at room temperature, followed by treatment at 40C, until the chemicals had reacted. They were given an antichlor treatment in:.

10 percent (o.w.w. sodium sulphate,

5 percent (o.w.w.) sodium bisulphite, for 20 minutes at room temperature.

Both samples were then rinsed and removed from the bath, and one was dried at 80C in a static drier. The other was treated with:

2.0 percent solids (o.w.w.) non-ionic polyethylene emulsion (Mykon SF),

0.5 percent solids (o.w.w.) polyelectrolyte (Primafloc C7), I at a pH of 5.0 for 15" minutes at C and a 30:1 L.R. The pH was adjusted to 5.0 with dilute acetic acid.

Sample Area Shrinkage Pre-treatment and polymer treatment 6 Pretreatment only 34 Untreated, scoured 35 EXAMPLE 4 3 Samples of lambswool fabric were given a pretreatment identical to that of Example 1 with the exception that 1 percent of active chlorine was used.

One sample was dried at 80C.

The second sample was impregnated with polymer emulsion by immersing it in a bath containing:

7.5 grams solids per litre non-ionic polyethylene emulsion (lberlene P.E.),

l.0 grams solids per litre polyelectrolyte (Primafloc C7), at 40C. The sample was immediately passed through a squeeze nip so as to retain in the fabric 100 percent of its own weight of liquor. The sample was left for about 5 minutes and was then dried flat at 80C. I

The third sample was treated in the same way as the second with the exception that the polyelectrolyte was omitted from the bath. Area shrinkages after a 60 minutes. litre Cubex test, were as follows:

Sample Area Shrinkage Pretreatment polymer and polyelectrolyte 0 Pre-treatment polymer only l6 Pre-trcatment only 14 Untreated 33 It is likely that the polyethylene exhausted on to the wool fibres of the second sample, but was deposited on to the third sample by removal of the water by evaporation.

EXAMPLE 5 Samples of worsted serge were pre-treated with 0.5 percent chlorine in a manner identical to Example l.

The following polymer treatments were then carried out, in each case the bath being maintained at 40C, until exhaustion was completed. The samples were then dried and tested in the Cubex 25 litre test for 60 minutes.

Exhaustion of the cationic emulsion in the presence of the Primafloc C7- was slow (up to 1 /2 hours). Also, as can be seen, the shrink resistance conferred by these emulsions was not so great as that conferred by the non-ionic emulsion.

EXAMPLE 6 Samples of fabric, knitted 2 end-as-l, from a 2/20's worsted spun yarn, were treated with chlorine by a process similar to that described in Example 3. The modified samples were then given the polymer treatments indicated below, the area shrinkage results from a Cubex l5 litre/60 minutes test also being given in each case.

Polymer treatment Area Shrinkage (a) 0.l% solids (o.w.w.) Primafloc C7. Dry

at room temperature followed by 0.75% solids (o.w.w.) Bradsyn P.E.

(b) 0.l% solids (o.w.w.) Primafloc C7 followed by 0.75% solids (o.w.w.) Bradsyn P.E. without intermediate drying.

(c) 0.1% solids (o.w.w.) Primafloc C7. Dry at room temperature followed by 0.75% solids (o.w.w.) lberlene P.E.

(d) 0.1% solids (o.w.w.) Primalloc C7 followedby 0.75% solids (o.w.w.) lberlene P.E. without intermediate drying. I9

(c) 0.1% solids (o.w.w.) Primafloc C7 0.75%

solids (o.w.w.) lberlene P.E. in same bath. 4

(f) Pre-treatment only 37 EXAMPLE 7 2 Swatches of fabric knitted 2 ends-as-l, from 2/20s worsted spun yarn were treated with 2.0 percent (o.w.w.) active chlorine from sodium dichloroisocyanurate at a pH of 3.5, a 30:1 L.R. and 25C until all the chlorine had reacted. The samples were then neutralised by addition of 4.0 percent (o.w.w.) sodium sulphite. They were then rinsed, hydroextracted, and one was dried at C in a static drier.

The other was treated with:

0.75 percent solids (o.w.w.) non-ionic lberlene P.E.

+ 0.] percent solids (o.w.w.) Polyteric CA.

The treatment was carried out at a 15:1 L.R. at 40C for 10 minutes, and the treatment liquor was seen to go water-clear, indicating exhaustion of the lberlene P.E. had occurred. The sample was then hydroextracted and dried at 80C in a static drier. After a 60 minute, 15 litre Cubex wash, the samples shrank as follows:

Sample Area Shrinkage Pre-treatment only Pre-treated lberlene P.E. Polyteric CA EXAMPLE 8 had reacted. The samples were then neutralised by the;

Polymer Treatment Area Shrinkage 1.0% solids (o.w.w.) Vinamul 6000 (P.V.A. emulsion, anionic) 9.7 1.071 solids (o.w-.w.) Vinamul 65l5 (P.V. acetate/caprate emulsion, anionic) 55 L07: solids (o.w.w,) Calatac V.B.

(P.V.A. emulsion, non-ionic) 8.8 1.0% solids (o.w.w.) Calatac ASX (polymethyl methacrylate emulsion, cationic) 7.6 Chlorine pre-treatment only l9.2

In each case 0. i'giereeaisaiia zaiwiw; massa e? was added to the four polymer treatments, and after the.

b. treating the modified wool with an aqueous emulsion of an emulsifiable polymer so as to deposit polymer on the fibers of the wool, the improvement which comprises performing step 5 (b) .by treating the modified wool with waterdispersible polymers having amolecular weight of from 20,000 to 10,000,000 viscosity average and having an exclusively carbon atom backbone to which are attached units of the formula wherein A is a C2 to C3 alkylene group in which different carbon atoms are linked to the two nitrogen atoms and as the emulsifiable polymer emulsion, a polymer of acrylic acid or a substituted acrylic acid, a homopolymer or copolymer of vinyl acetate or a polyolefin, and drying the thus-treated wool at a temperature of not more than 100C.

2. A process as claimed in claim 1, wherein the aqueous emulsionvof the polymer is a non-ionic emulsion.

3. A process as claimed in claim 1, wherein step b) is carried out as a batch operation and the wool is caused to remain in contact with the polymer emulsion until the polymer has completely exhausted on to the wool fibres. 

2. A process as claimed in claim 1, wherein the aqueous emulsion of the polymer is a non-ionic emulsion.
 3. A process as claimed in claim 1, wherein step b) is carried out as a batch operation and the wool is caused to remain in contact with the polymer emulsion until the polymer has completely exhausted on to the wool fibres. 